German reformer, born at Gunzenhausen, near Nuremberg, on the 19th of December 1498. His German name was Heiligmann, or, according to others, Hosemann. After studying at Leipzig, Altenburg and Ingolstadt, he was ordained priest in 1520 and appointed Hebrew tutor in the Augustinian convent at Nuremberg. Two years afterwards he was appointed preacher in the St. Lorenz Kirche, and about the same time he publicly joined the Lutheran party, taking a prominent part in the discussion which ultimately led to the adoption of the Reformation by the city. He married in 1525. He was present at the Marburg conference in 1529, at the Augsburg diet in 1530 and at the signing of the Schmalkald articles in 1537, and took part in other public transactions of importance in the history of the Reformation; that he had an exceptionally large number of personal enemies was due to his vehemence, coarseness and arrogance in controversy.

The introduction of the Augsburg Interim in 1548 necessitated his departure from Nuremberg; he went first to Breslau, and afterwards settled at Königsberg as professor in its new university at the call of Duke Albert of Prussia. Here in 1550 he published two disputations, the one De Lege et Evangelio and the other De Justficatione, which aroused a controversy still unclosed at his death on the 17th of October 1552. While he was fundamentally at one with Martin Luther in opposing both Romanism and Calvinism, his mysticism led him to interpret justification by faith as not an imputation but an infusion of the essential righteousness or divine nature of Christ. His party was afterwards led by his son-in-law Johann Funck, but disappeared after the latter's execution for high treason in 1566. Osiander's son Lukas (1534-1604), and grandsons Andreas (1562-1617) and Lukas (1571-1638), were well-known theologians.

Osiander, besides a number of controversial writings, published a corrected edition of the Vulgate, with notes, in 1522, and a Harmony of the Gospels -- the first work of its kind -- in 1537. The best-known work of his son Lukas was an Epitome of the Magdeburg Centuries.